In zoological nomenclature, synonyms are different scientific names that pertain to the same taxon, for example two names for the same species. The rule of zoological nomenclature is that the first name to be published is the senior synonym; any others are junior synonyms and should not be used. The International Code of Zoological Nomenclature (ICZN) is a set of rules in zoology that have one fundamental aim: to provide the maximum universality and continuity in classifying all animals according to taxonomic judgment. ... A taxon (plural taxa), or taxonomic unit, is a grouping of organisms (named or unnamed). ...

Synonyms are "objective" if they unambiguously refer to the same taxon; this is the case if they refer to the same description or the same type specimen. Otherwise the synonyms are "subjective", meaning that there is room for debate: one researcher might consider the two names to refer to the same taxon, another might disagree. Type specimens When a new species is discovered, more important than creating a new and unique name for the species is developing a reasonably detailed description. ...

For example, John Edward Gray published the name Antilocapra anteflexa in 1855 for a species of pronghorn, based on a pair of horns. However, it is now thought that his specimen was an unusual individual of the species Antilocapra americana published by George Ord in 1815. Ord's name thus takes priority, with Antilocapra anteflexa being a junior subjective synonym. John Edward Gray. ... Binomial name Antilocapra americana Ord, 1815 Subspecies The pronghorn (Antilocapra americana) is the only surviving member of the family Antilocapridae, and the fastest land animal in North America running at speeds of 54 mph (90 km/h). ... George Ord (1781 - January 24, 1866) was an American ornithologist. ...

Objective synonyms are common at the level of genera, because two researchers may independently arrive at the conclusion that a species is sufficiently different from others in its genus that it needs to be given its own genus. Thus each names a new genus with the same type species; these are objective synonyms. Type specimens When a new species is discovered, more important than creating a new and unique name for the species is developing a reasonably detailed description. ...

At the species level, subjective synonyms are common because an unexpectedly large range of variation in a species — or simple ignorance about an earlier description — may lead a biologist to place a newly discovered specimen in a new genus. However, objective synonyms are quite rare. An example is the tarpan (the European wild horse) which was described by Johann Friedrich Gmelin in 1774. In 1784 Pieter Boddaert named the tarpan Equus ferus, referring to Gmelin's description. Unaware of Boddaert's name, Otto Antonius published the name Equus gmelini in 1912, again referring to Gmelin's description. Since the two names refer to the same description, they are objective synonyms. Binomial name Equus ferus Boddaert, 1785 The Tarpan, Equus ferus, was the Eurasian wild horse. ... Johann Friedrich Gmelin (August 8, 1748 - November 1, 1804) was a German naturalist and botanist. ... Pieter Boddaert (1730 - 1795 or 1796) was a physician and naturalist. ...

See also

• synonym (botany)
• synonym